Earlier studies from this laboratory showed that tissues in or near the pharynx, in both man and rat, secrete a lipase that acts in the stomach, at pH 5.4, to hydrolyze triacylglycerol to di- and monoacylglycerol and fatty acids, and that this is the first step in digestion of dietary fat. The products formed are amphiphilic and facilitate emulsification of triacylglycerol before it leaves the stomach. The objectives of this project are: 1) isolate and purify pharyngeal lipase from tissues of rats and other species and from pharyngeal secretions of man, 2) characterize the mode of action of pharyngeal lipase, 3) study the regulation and mode of secretion of the enzyme, and 4) determine the role of pharyngeal lipase in fat digestion in normal and diseased states, in both infants and adults. Recent studies of the lipolytic activity present in rat lingual serous glands indicate that pharyngeal lipase acts primarily in the core, not at the surface of lipid droplets, and that its action is not dependent on the presence of fatty acid acceptors (albumin or Ca ions) in the incubation medium.